1. Field of the Invention
The invention relates to a method for operating KVM switch with independent on-screen display (OSD) and control channels, particularly to the method that uses an OSD unit to process OSD signals and an OSD video switching circuit to switch the ON/OFF of the display of the OSD synchronization signal, OSD menu video signal and OSD background video signal, keeping display settings unchanged on the OSD picture and facilitating OSD related operations.
2. Description of the Related Art
When a computer fails to meet operational requirements due to working or updating factors, adding a computer or continuing to use the replacement machine is the most common solution; but under the condition of limited space and insufficient budgets, these ideas can seldom be achieved in the past. However, thanks to rapid development of electronics and information technology, now two (or more) computers, whether new or old, can share one keyboard, mouse, monitor and even loudspeaker, microphone and any peripheral simply through connecting in series to a KVM switch. Thus, users can not only have more space to work more efficiently, but also reduce the cost in purchasing peripherals.
KVM switch is a switch that integrates keyboard, video and mouse. In other words, KVM switch allows users to switch displays among multiple computers merely with a single set of keyboard, video and mouse. This not only helps reduce the number of operating equipments in the multi-computer environment, but also allows the user to manage different computers or servers synchronously through rapid switching from one computer to another, without interrupting operations of the computer from which the switching is performed, thus making operations easier.
As KVM switch becomes popular, manufacturers have developed KVM switches with on-screen display (OSD) functionality, which display a control panel on the monitor to facilitate operations and adjustments by users, as shown in FIGS. 6 and 7. For the KVM switch with usual OSD functions, OSD video signal are inserted into horizontal/vertical signal of computer video, so as to make the OSD operation picture directly overlap on the original computer picture. However, when the display settings of computers are different, the size or location of characters of the OSD operation picture will vary from one computer to another. This not only affects the degree of comfort of the user while viewing, but also makes operations using mouse or touch screen more troublesome and difficult. Besides, usually it is easy to form an interface channel into which unauthorized users can intrude through the OSD operation interface. As long as the unauthorized users intrude into any part of the MCU, switching circuit, firmware program area or data storage area, they can intrude into any externally connected computer due to connectivity of KVM blocks and connection with external computers, thus resulting in poor security and safety protection functions.
A KVM switch A comprises a switch circuit A1, a switch control and processing chip A2 and an OSD chip A3. The switch circuit A1 is connected with a plurality of computer connecting interfaces B and a monitor C, while an operation and control device D is connected with the switch control and processing chip A2. Since the switch control and processing chip A2 not only performs various operation functions of the KVM switch, but also needs to perform processing and calculation of the OSD display functions. However, the size of the program memory of the switch control and processing chip A2 and the number of the I/O pins will limit the OSD display functions. Moreover, due to increasing execution burden and the share of resources of the switch control and processing chip A2, the on-screen display functions are limited.
Basically, for the KVM switch with OSD functions available in the market, there is a main control unit inside for performing control. When switched to display the OSD operation picture, the OSD operation picture (On-Top) is directly displayed on the screen and overlaps on the original computer picture. There are problems and disadvantages with the displayed OSD operation mode and picture as follows:
(1) because OSD picture depends on the display setting parameters of a computer connected by the KVM switch, and when the connected computers have different display setting parameters, the OSD display characters change with the setting parameters of the computers and produce a deviating phenomenon of display characters, image and location, thus resulting in poor visual adaptation of consumers. Furthermore, for the deviation of the OSD display position is not fixed, the operator cannot achieve the function of controlling with mouse or controlling with touch panels.
(2) since the switch control and processing chip A2 of the KVM switch is also used to assist in processing the OSD functions, it will have impact on the size of the program and data memory used by the micro-processor chip of KVM switch and on the number of I/O pins, and will increase the operation burden of the switch control and processing chip A2 and occupy the limited resources, without making full use of the functions of the switch control and processing chip A2 and OSD operation pictures. Moreover, when online update is required, only the original OSD basic operation functions of KVM switch can be updated in a limited scope due to the above limitations in hardware structure (reduction in memory capacity available and the number of I/O pins), and it is impossible to update functions of KVM switch and OSD system effectively.
(3) since the OSD system and KVM switch share the same switch control and processing chip A2 and other resources and cannot separate all computers controlled by them, the standards of IT security required by the secure KVM switch cannot be reached, such as the requirements for the general standards of NIAP and the human interface device.
(4) the OSD system and KVM switch share the same switch control and processing chip A2, while the switch control and processing chip A2 has a plurality of pins, and the switch control and processing chip A2 occupies memory and hardware pins in order to process a large number of signals and transmit different signals through a plurality of pins respectively, and it will result in higher prices of the switch control and processing chip A2 and increase the cost of KVM switch accordingly.
The above-mentioned problems and disadvantages of a conventional KVM switch are just what the inventor and others involved in this field need urgently to improve.